Radiant floor heating system has major leak, need to replace
Guess it depends on what you want. There are many options available in the hot water market from baseboard type convectors, (big drawback is they take up a lot of wall space and you shouldn't put stuff up against them) to some fan forced units that take up a very small amount of space in the room. You can also get heated towel racks that would provide heat to the bathroom areas and give you nice warm towels at the same time.
I would assume that you would have multiple loops in the current floor system, could you not identify which loop is leaking and just get rid of that one loop for now?
The other consideration is if you would like air conditioning. You won't have that option with hot water, but you may consider something like ductless split heat pumps with electric strip heat. (depends on where in the country you live as far as how cold it gets, and what you pay for electricity)
The forced air option sounds pretty pricy to me, but I haven't seen the job, you may want to get a couple more quotes to compare prices before you bite at that one.
Really the options can be almost endless, just depends on what you want, and what you have to spend.