I have no previous efi experience but watched with intrest as Fitech came along and made efi "more" mainstream with an affordable price, but not pulling the trigger waiting to hear/read and watch feedback from other people.
I finally went with Holley Sniper. And it was a painless install everything just worked if you follow the instructions to a the letter.
it was first true strat on the first reveloution of the starter the very first time, and it was dead even, not a miss or rpm fluctuation. it is set up to run out of the box, but the tune is not a fuel efficent one, it is set up so you can hop in and drive it.
The tuning aspect is great, a lot can be done with the handheld, but the true gem is the holley efi desktop/laptop software, pop out the SD card in the handheld controller after you export your base tune with learning and you can tweak it with endless posibilities.

*Note: i strongly suggest an tanks inc og similiar efi gas tank with in tank pump.
Next year i will install the brand new holley EFI distrbutor that goes with the sniper system, just announced a month ago
https://www.holley.com/products/fuel_systems/fuel_injection/sniper_efi/hyperspark_ignition/parts/565-314BKMy one complaint is the temprature sensor that read wrong out of the box, as with most other sniper efi user, i had to buy a generic GM coolant sensor, to get temprature enrichment and fantriggers to work correct, but that was like 25 bucks extra.