I been doing the hobby for over 30 years. I have had nitro and electric from many different manufactures, and if you know what youre doing nitro can be alot of fun. Noise, adjusting settings, oil on everything all adds to the flavor of them. And when tuned in properly can be a ton of fun, but you need to know what youre doing. BUT if you want to have a lot of fun, not have to tune in all the time, and want balls out speed $500 off ebay gets you one of these:
http://www.youtube.com/watch?v=bsIgwmth3EM
That is mine and runs about 40-45 minutes on a tank of gas, yes gas, with 2 stroke oil mixed in. Its a weed eater motor strapped in a 1:5th size buggy and I can tell you its more fun then electric or nitro. You can pick it up from a guy called rovanrc on ebay, he has a ton of them and well worth the price considering the HPI build will cost you $1200 and not have a kick ass 2.4ghz radio, or updated exhaust. I have wrecked it, hit a tree, and flipped it end over end MANY times and still wants more. So if you have the room for one, thats what I would say pick up. Uses pump gas vs nitro, and 4x the run time electric would give you, plus when you pull that sucker out and people hear it be ready for a crowd. All you need to get started is a bottle of 2 stroke oil ($2), and 2 gallons of pump gas (high octane), batteries for the controller and go out and bash the sucker.
But what ever you pick out you will have fun.
What I own right now is:
Kyosho Madforce Cruiser
Kyosho Madforce version one
Kyosho Mini Mega Force
HPI MT2
Traxxas T-Maxx 3.3
Traxxas Slayer Pro 3.3
Ofna Hyper 8.5 Pro
Ofna Picco Off Road
Redcat Racing Earthquake. Going to be here on the 5th and can tell you if its junk or not. First one, and couldnt pass up a big block, 2 speed MT for $265 including the starter pack and a quart of nitro fuel. Had to give this brand a go.
Rovan (HPI 5B Clone) Baja 26cc
Rovan Baja 30.5cc with a ton of aluminum. BTW ALL HPI 5B parts will fit the Rovan, or King Motor builds. Video of this one coming soon.
And once I sell my planes and HT Amp Im going to buy a Ofna LX2 Nitro.
Check my sig if you like to see most of them in action. And with nitro, break in is very important and if you skimp on it, it will give you problems down the road, like not keeping a tune, lack of power, blowing out glow plugs often, and so forth. So make sure that if you do do nitro to follow the instructions from the manufacture closely and to the letter. It will pay off in the long run.