Long term investment, which deck.

[Fling]

On the (great) advice of some players here I ended up building mono blue merfolk, and have been playing and enjoying it for some time now. The last month or so I have been wanting to start working on something new, and since I don't know what yet, I spent that time working my way into a set of Tarmogoyf. Now I'm just not sure what I want to build, I've narrowed it down to Zoo, Counterbalance (probably a Bant oriented version) or maybe even 43 lands. I like all 3 decks, I'm just not sure which one I prefer, and since I will have to acquire some expensive cards no matter which way I go, I want to make the best investment I can.

Since I don't really favor one deck over the other, I want to build whichever deck will be viable for the longer term, hold it's value the best, and preferably use cards that have applications in more than one top tier deck. The lands deck seems like it might be the worst choice there, Zoo somewhere in between, and Countertop the best bet, but I wanted to get some opinions, since it's going to take a lot of work for me to build any of the above, and I want to do it right. I'm open to any other suggestions as well, thanks.

[Ozymandias]

If you already have merfolk and Tarmogoyfs, you should start by picking up a set of Tropical Islands as well as some blue fetches. That way, you are half of the way to Countertop, capable of playing U/g Merfolk if you like, and only 4 Volcanics away from Tempo Thresh as an added bonus. Then start in on Tops and CBs, and then pick up whatever Tundras and Volcs you need to finish Countertop.

[TheInfamousBearAssassin]

Some version of a UWG Aggro-Control deck will be viable until they ban Force or StP. So go with that one.

[(nameless one)]

I would say Canadian Thresh as it never gets old and has no virtual bad matchup. If I had the cash, I would personally build one but I dont own any = Dual Lands or Tarmogoyf.

[miko]

I also tend to advice Canadian Thresh, because it is pretty cheap if you got the land-base and Goyfs. Dazes, Stifles, Ponders and Brainstorms even Mongoose are not very expensive. Just Force of Will will be $20 at least.

[Eddy Wally]

If you want a deck with cards that will hold their value, I suggest something with the 40 duals in it together with 4 copies of Progenitus (so you'll be able to hardcast it). Add 4 textless Wrath of God and 4 textless Damnation for creature controll, 4 Elspeth which can spam tokens to keep you alive, and 4 copies of the new Jace to dig for your kill cards.

I guarantee you that this deck will hold its monetary value, especially with the current reprint policy. It may not be able to take on tier 1 decks though.

On a serious note: have you considered an elf tribal deck with tarmogoyf? Elves are always a blast to play with.

Don't go for zoo, that manabase will cost you an arm and a leg.

[Atwa]

If you need to invest in a deck, I would go with a deck that shares a lot of cards with other decks. Some kind of Thresh or Bant seems pretty safe.

I wouldn't go for Lands, as a lot of the more expensive cards have limited use. Manabond is only played in Lands, Exploration is only getting played in Enchantress and I believe the biggest investment (Tabernacle) is in bubble at the moment, which will burst somewhere along the line. If I didn't own 1 yet, I would never ever buy one at the current price, way too risky. I'd even sell it right now if I didn't need it for my Legendary collection.

Go for Tarmogoyf, Tropicals, Tundra and Blue fetch. Those building blocks along with the FoW you already have make a lot of decks available for you.

[from Cairo]

If you want a deck with cards that will hold their value, I suggest something with the 40 duals in it together with 4 copies of Progenitus (so you'll be able to hardcast it). Add 4 textless Wrath of God and 4 textless Damnation for creature controll, 4 Elspeth which can spam tokens to keep you alive, and 4 copies of the new Jace to dig for your kill cards.

I guarantee you that this deck will hold its monetary value, especially with the current reprint policy. It may not be able to take on tier 1 decks though.

On a serious note: have you considered an elf tribal deck with tarmogoyf? Elves are always a blast to play with.

Don't go for zoo, that manabase will cost you an arm and a leg.

... In summation: "duals are a good investment, don't build deck X, the duals are expensive" ?

@ OP: I'd pick up bant stuff or canadian thresh stuff as most everyone has suggested. Both archetypes have proven track records of surviving meta shifts. If you like Merfolk's playstyle I would lean towards Bant Agro or Canadian Thresh rather than a CB/T build of UGW, but either way once you have the lands the shifts between these archetypes isn't too costly.

[Eddy Wally]

... In summation: "duals are a good investment, don't build deck X, the duals are expensive" ?

@ OP: I'd pick up bant stuff or canadian thresh stuff as most everyone has suggested. Both archetypes have proven track records of surviving meta shifts. If you like Merfolk's playstyle I would lean towards Bant Agro or Canadian Thresh rather than a CB/T build of UGW, but either way once you have the lands the shifts between these archetypes isn't too costly.

Part 1 of my post was meant less than 100% serious...

[Nizmox]

I went through a similar exercise myself when I started playing Magic again, and being an old school player I only wanted to play Legacy.

I basically went through the Decks to Beat at the time (and some of the Established Decks) and took note of what cards were found in multiple decks. I figured these were the best cards to aim for, because if I wanted to build another deck later I'd hopefully have some of the costly cards.

Probably stating the obvious, but the most used cards I found were....
Dual Lands (Badlands, Scrubland, Plateau and Savannah were the least useful, in that order)
Fetch Lands
Tarmogoyf
Force of Will
Lion's Eye Diamond (if you like combo)

So you want to pick a deck containing as much of the above as possible whilst minimizing expensive cards that only 1 or 2 different decks use.

By this logic I think Lands is a very bad choice as others have mentioned. Cards like Maze of Ith, The Tabernacle at Pendrell Vale (Very Expensive), Manabond and Exploration are expensive and have little relevance in any other deck.
Canadian Thresh is definitely my pick, as it FoW, Tarmo and the expensive, yet most useful duals.
In addition, it has virtually no cards that are useless in other decks and cards like mongoose that aren't heavily played are dirt cheap. So yep, Canadian Thresh...

EDIT: Thinking about it more, i'd actually probably go the Bant route as it has most of the same cards, but I think Tundra's are a better investment than Volcanic Islands. As to what variety you play (Bant Aggro, Survival, Countertop and/or Prog, that's up to you).

[Fling]

Sounds like a plan. I looked at some more versions of the counter/top decks and I'm not terribly far off from some. I currently have all the standard legal fetches as well as a set of Windswept Heath, all the fish stuff ('folk, force, wasteland, daze, etc) and goyf. I think I will follow the plan of switching to Ug merfolk by getting 3 or so Tropical Island, adding my Misty Rainforest's and a couple of Scalding Tarn, and probably throwing a couple of Grip in the board, since it looks like I need the tropical's regardless of what I do.

After that,it sounds like picking up Counterbalance and Top, and deciding what else I need of the W/U duals/fetches I need to pick up is the next step.

Thanks for the help and other advice you have!