Although there's nothing wrong with flying /A, you will find yourself wanting to fly /G. Since conventional approaches and navaids are disappearing in favor of GPS approaches, an IFR GPS becomes minimum equipment just to get in to many airports. I've spent a lot of time flying with different IFR GPSs, and the 430/530 series is definitely the best from a perspective of user friendliness and has the added benefit of being extremely popular and likely to continue to be supported for years to come. So, I would tend to look for a 430 at a minimum.
To upgrade a 430 or 530 to its W equivalent is $3,000 and involves swapping the unit, the antenna, and the antenna cable (if your cable isn't already of sufficient quality). It's a very simple task that any A&P can do, so if you find an apropriately priced plane with a 430 that meets all your other criteria, wouldn't quibble over not having the W and do the upgrade.
I'd also recommend looking for a 530 if you can. The 530's larger screen I find does make a difference, and its primary nav page (which I consider to be the IFR page) is great. Just some input.