You're in very very good hands with Rick.
As others have said, your choice depends on what you're looking for. You probably won't notice much of a difference going to 3.73's and no other new mods. There will be a difference but it'll be subtle.
If you go with 3.90's you'll notice a significant change (you'll feel like you just added 50 hp even though you didn't actually gain anything) but your gas mileage will suffer slightly and you're liable to need tires more frequenly
Also be sure to take your long term plans for the car into account when making your decision. Are you going to stay at your current power level or add more?
If it were me I'd go with the 3.90's but it's your car... Ask yourself if three months down the road you're still going to be happy with the mild change or wishing you'd gone with the 3.90s...