I say kegging system with at least 4 kegs, that way when you do make 10 agllon batches you don't have to bottle over 100 beers. If I could go back and start brewing all over one of the things I would do differently would be to start out kegging...and start out AG, but hindsight is always 20/20.
Kegs are so versatile, you can condition in the keg, a single vessel to bulk condition all your beer is...awesome
You can still botle from the keg, so why only bottle at all...don't get me wrong I love the novelty of bottling, and I think some beers must be bottled, but kegging gives you the versatility to do both.
Having co2 to purge fermenters, or secondaries is sweet.
The list goes on...
If you plan to brew often - keg, and keg soon. If you don't mind the bottling process, and want to increase your brewing volume go with the pot, but a sanke keg off of CL for $25 plus all of your weldless fittings (ie. ball valve, sight glass, etc...) will be less than buying a clad bottomed pot.
Having said that, I just finished my DIY kegerator a month ago, and I did buy a B315 pot form morebeer last year (15 gal kettle with ball valve and thermo fitting). I do highly recommend the kegging system over the pot, from experience.