Ethereum and Monero would be my vote. I hold a small amount of each, so I'm biased but then again why wouldn't I hold what I recommend?
Ethereum: Sure, it's possible to incorporate smart contracts and other features on top of bitcoin via counterparty and the like. However, since ETH has such a smaller user base and very centralized development process, speed of development will be much quicker over the next 1-2 years while it matures. Anything more than 1-2 years out is too far, but I think that is a reasonable time frame to look at.
Monero: Similar to the above, Monero has a very targeted approach to privacy, fungibility and secrecy. It does a good job of covering all needs whether that of dark/grey markets or that of a law abiding storefronts since transactions can easily be revealed with view keys. I don't see Bitcoin gaining these features in any sort of useable fashion for at least 2 years since they'd need to be built into a sidechain first. Sidechains won't be fully trusted until the federated model can be removed and this may take even longer than 2 years, although I rather hope that it won't take this long.
thanks for your input.
Yes, maybe you are right about ethereum and I need to revisit my position. It has a different codebase, so that's a plus also

About XMR and sidechains, that won't work because you will only have the anonimity, but not the fungibility. I posted about this a few months ago:
I don't know all the technical details of his proposal, but just think theoretically here:
A sidechain which works perfectly like Monero is introduced, what are the consequences?
(1) people who send BTC in the "ring signature sidechain" (RSSC), taint their BTC who are not entering the RSSC. If their identity is matched with the same identity as who put BTC in the RSSC, this person can become "flagged".
(2) people can transact within the RSSC anonymously. This has value. (The same value as transacting in XMR).
(3) people who want to get their BTC out of the RSSC, immediately taint those BTC. It's even easier to taint these BTC than BTC put through a mixer or using coinjoin because you don't need to do extensive chainalysis. If/when regulation starts to come down on payment processors and/or miners (see
my reddit post about fungibility for more info on the risks of tainting your BTC), these BTC's will be hard to spend in the 'regular economy' or even transact with.
People probably want to avoid (3) happening, so they keep their BTC in the RSSC. But this has disadvantages too, your BTC are locked in this particular sidechain! If another (better) sidechain comes out, you can't migrate them (or maybe you can, don't know if the sidechain proposal allows settlement directly on another sidechain or not). Also, if miners and/or nodes stop supporting the 'obfuscation sidechains' like RSSC (assuming they even wanted to touch them in the first place), you can't even use the transaction system (2) and your BTC became worthless in an unsupported sidechain.
Why risk all that and not just buy XMR? you can always dump them if the market is starting to switch towards another (better) anon cryptocoin?