Foch B probably has the worst chassis at tier X. Armor isn't great, weakspots are large and obvious, gun arc is awful, mobility isn't its strength, and you have to spam gold to be relevant in most games. It's easily the most awkward tier X in my garage to play. I find it difficult to dictate the terms of engagements in it like other TDs can... you don't do well at long range, and getting in close means you're exposing your awful weakspots. @Rexxie seems to like it, though, and I'd trust their opinion over mine for better players than I.
AMX M4 isn't great either, but at least the 130mm is fun to blap people with and you have enough mobility to choose your engagements. It's overshadowed by the E5 and Sconq, but I find it fun to play. There's something about having low expectations going into a match that lowers the pressure I put on myself, which leads to more enjoyable gameplay. It's why I still have the AMX 40 in my garage.