Does generator brand make a difference?

If you have a 50 amp connection on your RV it is actually a 240 circuit, ie. 2-120 volt legs, but the extra leg in a 50 amp versus a 30 amp is ONLY for a second A/C unit, unless someone has changed the wiring. You would still not necessarily have enough amps available from a 50 amp 240 volt genset to run your entire AC load and the gen would need specific R/V wiring (connector) to connect properly. The 2 2000 watt gens ie. Honda/Yamaha etc. use a parallel cable hook up that runs them together on 1-120 leg, and keeps them in phase to provide the added capacity. Also even 2 2000 watt Hondas may not run your 15K A/C depending on it's efficiency or it may suffer an early demise do to running too hot. I have a pair that runs my 15K and microwave ok, but will barely run my friends 15K A/C and then it is at it's absolute limit and won't restart until it is off for a long enough time to cool down.