If space is an issue and you want to do low n slow smoking, then you might want to consider getting a vertical smoker. Some examples for you to look into and their common bbq acronyms (there are a lot of those to get your head around!)
WSM - Weber Smoky Mountain. A "water smoker" where the fire bin is below a water pan.
ProQ Excel range - similar to WSM but cheaper
UDS - Ugly Drum Smoker - very easily built home made smoker that costs about £50 to make (this is what I cook on and love it)
ECB - El Cheapo Brinkman, aka Brinkmann Smoke n Grill. The bottom of the range water smoker. I had one. I hated it. Needs modifications just to make it usable.
If you want to have a unit you can smoke on *or* grill, you may be best looking at a large kettle similar to the "OTP" - Weber One Touch Premium. No doubt Weber make a damn good quality barbecue, but they are rather expensive compared to unbranded equivalents. Just make sure whatever kettle you go for has air inlet baffles as well as exhaust baffles. You can also do direct grilling and indirect smoking on an offset (horizontal) smoker but they take up more room.
Everyone has their own preferences and favourites and there isn't a right or wrong answer. I love my drum smoker, it was simple to build, very cheap, takes up little floor space and burns efficiently and predictably. If money was no object I would probably have bought a WSM, much like I would have an Apple computer instead of a home built Linux box, but that's not the case
