If you're looking to buy, this is what I have and some ideas about each:
Brinkmann Horizontal - I like this smoker because of it's versatility. You can use charcoal or wood depending upon the whole "direct or indirect" method of heating you prefer. Also, you can't beat the capacity of the unit. On the other hand, you will need to keep a close eye on your temps. when cooking. I prefer not to exceed 215 on a long smoke so you need to be very observant (at least I do).
Brinkmann Vertical (Gas) - I like this smoker because I can set a temp. and it will stay constant with very little supervision. This isn't a "purist's" unit but it does the job comparably IMHO. It has a water/drip pan above the wood pan to keep moisture flowing and keep grease away from your wood and flame. The drawback of this unit is capacity. It has two food racks, stacked, but they are relatively small. If you have two vertical rib racks you can smoke a full rack of ribs (split in half) on one level. You can use the other rack but I prefer not to due to uneven heating. Rotating would always work but that's less time watching football or hockey. Also, the wood pan is relatively small so it works better with chips vs. chunks and chips burn-up faster than chunks.
Either way, your neighbors will REALLY love you once you get started...they'll know when you're smokin' and invite themselves over for a cold one and some smoked meat!