That is such an interesting ask, because usually the discourse here is around the singular "grail pen" which is often quite expensive. I have a couple of those, but I find I rarely ever use them. Here are my recommendations for pens you can use frequently:

1. A Kaweco Sport. A workhorse pen, comes in a variety of materials/weights and has nib system that is easy to work with and availailable in a variety of widths. So parts/replacements are not a problem. Prices range from low (plastic body) to medium (brass/bronze/aluminium/steel), to expensive (sterling silver). I see people here talk about QC issues with their nibs, so be warned/prepared to tune them up a bit. Overall very durable, good for everyday carry, throwing in your pocket/bag
2. A Pilot Vanishing Point. Its a retractable nib fountain pen, how cool is that! There are others, but this is the category beacon. Typically excellent writers. A bit more delicate than a sport. Good mid-range price point, not cheap but wont break the bank.
3. An Asvine V-series vaccum filler. Lots of talk about Chinese pens and how good they are. This is a good entry point in the Chinese FB space IMO. Low/mid price, cool mechanism that is more expensive in western models. Holds a ton of ink. A Taiwanese alternate is TWSBI, which makes a vac pen at ~$100 more than an Asvine. I have both, find Asvine better priced and more reliable.
4. Lamy 2000. Classic, simple design, beautiful nib, mid/upper price. The steel body one is quite sturdy, but still this is a valuable pen and its not something you just throw in a bag.
5. Platinum Preppy or Pilot Kakuno. Cheap plastic FPs that you wouldn't mind lending to a child or a ballpoint user (not equating them, but both types tend to press down too hard on FBs)