Mares is less popular with certain groups of divers for reasons that have nothing to do with the quality of their regulators, which is at least as good as their primary competitors.
If you look through that old thread you'll see people complaining about parts availability issues that were resolved over 15 years ago, the size of the dealer network in the US, and resentment over Mares shuttering Dacor, a bankrupt US scuba equipment manufacturer that Mares' parent company purchased for its dealer network and brand name. There are also complaints about the price of their new regs.
As to the tech community. First off, Mares is well represented in the ice and cold water community. It isn't particularly popular for cave diving for three major reasons. First is their stupid corporate policy of insisting on selling their regs (except octos) only in limited combinations of first and second stages. These packages rarely line up with tech divers immediate needs and even when they do, divers have to take into account that they may have difficulty or additional expense adding the exact stages they want in the future. A second reason is that the hose routing of their classic second stages isn't particularly well suited for independent doubles, particularly in sidemount. The final reason is that cave divers tend to dive what their teammates are diving. And there's a strong preference for national brands there (regardless of where the reg is actually made). So, in Britain it's Apeks and in the US it's Scubapro, Halcyon, HOG, or Deep6.
None of these reasons apply to the OP. He is looking at buying used regs for single tank diving in a region where Mares has a solid dealer network. Either Mares or Scubapro will be fine, it is going to come down to the individual deals he can find. In the US, you can usually find much better deals on used Mares gear for all the reasons above, but I don't know if this holds true for Israel
If you look through that old thread you'll see people complaining about parts availability issues that were resolved over 15 years ago, the size of the dealer network in the US, and resentment over Mares shuttering Dacor, a bankrupt US scuba equipment manufacturer that Mares' parent company purchased for its dealer network and brand name. There are also complaints about the price of their new regs.
As to the tech community. First off, Mares is well represented in the ice and cold water community. It isn't particularly popular for cave diving for three major reasons. First is their stupid corporate policy of insisting on selling their regs (except octos) only in limited combinations of first and second stages. These packages rarely line up with tech divers immediate needs and even when they do, divers have to take into account that they may have difficulty or additional expense adding the exact stages they want in the future. A second reason is that the hose routing of their classic second stages isn't particularly well suited for independent doubles, particularly in sidemount. The final reason is that cave divers tend to dive what their teammates are diving. And there's a strong preference for national brands there (regardless of where the reg is actually made). So, in Britain it's Apeks and in the US it's Scubapro, Halcyon, HOG, or Deep6.
None of these reasons apply to the OP. He is looking at buying used regs for single tank diving in a region where Mares has a solid dealer network. Either Mares or Scubapro will be fine, it is going to come down to the individual deals he can find. In the US, you can usually find much better deals on used Mares gear for all the reasons above, but I don't know if this holds true for Israel