The best replacement for ftdi is prolific.

The best alternatives to ftdi are rated as following:
★★★★★  prolific
★★★★  uart
★★★★  atmega16u2
★★★  usbasp
★★★  pl2303
★★★  cp2102
★★  prolific chipset
★  silabs
★  max232
★  icsp

Your alternative for ftdi is not listed? Suggest!
Speaking about ftdi, one probably shouldn't forget about arduino.

Other search terms related to ftdi and their ratings are:
★★★★★ arduino
You have in mind a companion for ftdi and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ftdi in all years. Click on graph for more.
ftdi
prolific
uart