Firstly I choose PIC16F84-20, with which I have experiences. To ensure synchronizing with USB clock and speed increasing was used microcontroller clock 24MHz = 6MIPS (PIC was slightly overclocked). For one bit from USB processing were 4 instructions (4=6MIPS/1.5Mbit for LowSpeed USB). I reject this solution (after some time) - PIC is too slow (and in addition the no so good instruction set ...) .
Third try was successful: AT90S2313-10 (or AT90S2323-10, AT90S2343-10). This are RISC microcontrollers from Atmel production - AVR family. With comparison with PIC are slow crystal clock, but have 1 instruction per crystal clock (PIC16F84 has to 1 instruction per 4 crystal clock). In addition their instruction set and architecture is nearly to RISC. Again because of synchronization with USB clock I used overclocking to12MHz (AT90S23x3-10 are initially to10MHz only). In this manner I obtained more performance and 12MHz crystals are "easy to obtain" (with comparison to e.g. 10.5MHz - which is the multiple of LowSpeed USB clock 1.5Mbit/s too).