Fibreglass can be manipulated and shaped better and comes in any colour (that said the norm is grey), the downside it has to be done correctly with quality materials (which can be substituted for cheap products by some). 25-year guarantee. See Resin Roofs GRP system here.

EPDM is simply a rubber sheet stretched over the roof but money can be saved by replacing decking (if sound/dry). It can look very smart nut comes in black only. Generally about the same cost as GRP. 20-year guarantee

Felt is the cheapest option but degrades very quickly and has generally 10 years life. Peoples perceptions to felt are often also negative as a cheap covering. Brave to offer any guarantee over 10 years.