It's hard to say without more info. Really depends on your particular financial profile, scores and overall credit rating at the time of application. Generally, FHA loans can be had with higher debt to income ratios and are cheaper in reagards to lower down payments, but may come with much higher mortgage insurance premiums with scores in the high 500s to low 600s. If you have good to excellent credit, (above 680) Conventional loans will most often offer lower mortgage rates and PMI and are much cheaper in the long run.
Without knowing more information..... generally speaking it would be at 680 at a minimum but ideally 700+. If you're not putting down 20% then on your conventional loan your mortgage insurance is based off DTI and your score unlike the FHA MI.
