Either T5s or LED will grow corals. Supposedly T5s grow coral faster. Acro garden has acros growing under T5s on some tanks and under Reefbreeders photons on other tanks.
Going with all T5 will give the tank a bright, flat look with soft, diffused light, and no shimmer, which some people prefer. The Photon will give the tank darker look with some disco shimmer.
A 40 breeder is 18 inches wide. 2 T5 bulbs side by side are about 6 inches. A 6 bulb T5 fixture would most likely give 100% light coverage and give room to customize the color and spectrum. On 6 bulb fixtures you can usually turn off 1 set of 2 bulbs and 1 set of 4 bulbs separately as well if you don’t want all 6 bulbs on or if you want to have a staggered schedule.
If you go with the Photon and if shading is an issue later on, you could always go with a canopy and add a T5 retro kit for around $125 brand without bulbs or add RB Lumenbar strips.