A great kit on the market is the Apogee Level 2 kit - comes with everything except the electronics.
All the Patriots are cool and are easy to build.
The Wildman 3 Dual Deploy is dirt simple to make.
All the Wildman Darkstar rockets are awesome - the 4" Dual Deploy is a great rocket to start with, gives you the versatility of flying anything from an H to an L on it. Only issue is the dual fin setup - that may not be the easiest thing if you aren't used to it.
The Madcow 4" Fiberglass Super DX3 is a classic and another easy build.
Lots of great Black Brant II's out there - Composite Warehouse has a nice 4" kit in stock.
Would second the Missileworks series of electronics. Depends on the size of your rocket. If you go 3" or smaller, the RRC2 series is great - compact and easy to use. Although, I would recommend the newer RRC2L over the RRC2+. The ability to use the MW LCD controller makes the RRC2L much easier to use. You can program it at the field with no problem. If you end up going with an airframe 4" or larger, just spend the extra few bucks on an RRC3. The addition of a dedicated switch port makes it easier to wire up for your first try, rather than trying to figure out how to wire the switch in series to your battery port (as you will have to do on an RRC2). The other nice thing about MW is you can just buy one of their 3D printed sleds and make your life a whole lot easier for your first DD build.
Probably the only thing easier to use for electronics are the Perfecflite Stratologger CFs, but they are notoriously difficult to get ahold of.
As far as how small you can go, I have a fully dual deploy fiberglass minimum diameter 29mm rocket with an RRC2L in it. It flies nicely to about 1500 feet on an F52 and to about 9000 feet at 800 MPH on an I200. It uses a slick little 29mm sled from MW: