The best replacement for putty is silicone.

The best alternatives to putty are rated as following:
★★★★★  silicone
★★★★★  ssh
★★★★  kitty
★★★★  caulk
★★★★  wood filler
★★★★  openssh
★★★★  winscp
★★★★  telnet
★★★  securecrt
★★★  cygwin
★★  teflon tape
★★  spackle
★★  putty
★★  pomade
★★  paste
★  filezilla
★  silicone caulk
★  silicone sealant
★  tera term
★  bitvise
★  teraterm
★  flubber
★  paste hair
★  hyperterminal
  extraputty
  puddy
  rubber gasket
  puttytel
  exceed
  slime
  tunnelier
  secure crt
  gasket
  hair wax
  caulk window
  silicon
  pipe dope
  cygwin ssh
  tutty
  filler
  tape
  bondo

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

Other search terms related to putty and their ratings are:
★★★★★ xming
★★★★★ borax
★★★★★ serial
★★★★ x11
★★★ ssh key
★★★ cygwin
★★★ serial port
★★★ xmodem
★★ file transfer
★★ pem file
★ xterm
★ ssh
★ aws
gssapi
proxy
pageant
You have in mind a companion for putty and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of putty in all years. Click on graph for more.
putty
silicone
ssh