$3000 will probably keep you in carb 2 stroke range. I personally like Mercury V6's. they are light, make great power, you can use your existing wire harness and controls. Down side to mercs are the oil system is sketchy after it gets some age on it and the ignition can give some issues, water pumps on need to be replaced every year. My next recommendation would be a Yamaha V6, they are very reliable, oil injection rarely gives any problem and the ignition is bullet proof. Down side is they are expensive, parts are outrageous(especially the ignition), the trim system gives issues, trim motors are $$$, corrosion is an issue as well. Weight is about the same as the Johnrudes, but more than the mercs. Johnrudes round out the selection. Parts are cheap, the motors can be found cheap, plenty of aftermarket and good used parts. downside is the lower units fail quite regularly, the oil injection didn't work when they were brand new and should be disconnected, the ignition system gives issues, plastic carburetors(no longer available from the manufacture) and corrosion. Used 2 stroke Suzuki's are great motors, but their reputation for corrosion issues is earned, parts are rare and stupid expensive, good used lower unit bring a premium. I'd recommend staying away from them unless you find a nice fresh water, looks brand new, low hour, too cheap to pass up kinda deal.
Keep your merc for now, get used to the boat. If you find a deal on a motor, post it up on here and we'll give you our opinion on it.