If you're really set on building a 3 box that's going to last until live, just take TANK/CLR/ENC. In a couple years you'll be able to add mercs to help with dps.
All of the tank classes are completely fine. It mostly just comes down to personal preference.
The shaman will let you down in healing during mid-level expansions. DBG didn't really balances healers well from like 70ish - 100ish so a shaman will struggle there, especially in a small group. When I'm bootstrapping new teams on live, I always take a cleric until 100+. I'll sometimes switch to a shaman after that, but clerics are great for the whole game.
Enchanter is the only option for real CC in older content and can provide much needed DPC until charm starts to fall off in later expansions.
I personally think it's a mistake to try to build a 3-box now that will last you for four years. The game changes so much over expansions that it's hard to pick any setup that's great in all eras. Enchanter charm is really powerful now, but it's not even worth casting at high levels. Bards are great at high levels, but are strictly worse at everything for a long time (except run speed). You want ports now, but once PoP and the GH unlocks you'll never need them again. Etc.
It's trivial to PL new toons later on, so I think it's better to focus on what you're going to enjoy now and worry about later expansions when they unlock, if you're still playing these dudes. As @fohpo said, you can always use persona later on chase the meta.
There will always be more TLPs and more chances to try new strategies.
