Mushrooms, beans, aubergine
I LOVE mushrooms (Mr. Aulty, unfortunately, hates them). Beans too, but with beans and lentils I feel you have to use the right kind and/or find the ones you like. Black and broad beans are my favourite. Aubergine when they are in season. It gets easier once the produce selection gets better in spring and summer.
If you want to lose weight, be careful not to keel over into 'bread and pasta and fries are vegetarian'. Or eating too much fruit because they have so much sugar (as do smoothies).
As one of those weird people who can't with coriander, I find falafel a bit overrated ;-)
I used to like the veggie mince from Aldi but prefer to not use 'meat substitutes' if I can help it - not every meat dish has/can/should be recreated as a veggie version. Check out the recipe section on the Aldi and Lidl websites for inspiration (and recipes with a sensible ingredients list) - Aldi have a Mushroom and Pecan Wellington that I want to try and make into 'sausage rolls' (lol here we are again, recreating stuff ;-). Or try BBC Good Food.