Any 2 DP birds crossed with each other will give you decent meat birds. At this stage the strain of bird you have will be far more important than breed.
For some of the best crosses:
Indian Game (Cornish) x Light Sussex
Indian Game (Cornish) x RIR
RIR x Light Sussex
Wyandotte x Sussex
Dorking x Sussex
Dorking x Indian Game (Cornish)
These are traditional crosses for meat in the UK, but honestly, any 2 DP bird crosses will do, unless you specifically want more breast meat, in which case use either Dorking or Indian Game (Cornish) as one of the breeds.
A note about the Leghorn. Don't let people put you off about Leghorns for meat. People are spoilt with the fast growing broiler industry and they want tons of breast meat from every chicken. IF you appreciate legs/thighs, leghorns will work fine for you. I have personally tried a Leghorn x Dorking for meat and they were almost as good as my utility strain Indian Game (Cornish) x Sussex. The leghorn x droking were between 4-4.5 lb at 16 weeks, with excellent bone to meat ratio.
I can also tell you that before big business took over here in the UK Brown leghorn x Light Sussex was a popular cross because the pullets make ecellent and attractive layers and the cockerels were great for meat. The pullets were 4lb at 18 weeks and roos im guessing must have been about 5-5lb..5lb That is pretty respectable.