The best replacement for modelsim is quartus.

The best alternatives to modelsim are rated as following:
★★★★★  quartus
★★★★  active hdl
★★★★  isim
★★★★  aldec
★★★  vcs
★★★  questa
★★  ise simulator
★  questasim

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

Other search terms related to modelsim and their ratings are:
★★★★★ quartus
★★★★ xilinx
★★ xilinx ise
systemverilog
You have in mind a companion for modelsim and it is not yet here? Propose!



Google Trends

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modelsim
quartus
active hdl