What's the best maneating plant movie?

Clearly not this one... It's better than Island of the Doomed (Maneater of Hydra) (1967) and as it is a halfway decent film and technically competent, it is better than The Navy vs. The Night Monsters (1966). There are a couple of others with a plant monster, including The Mutations (1974) which is more entertaining but not very good.

I'm afraid the best is The Day of the Triffids (1963) although the 1980 BBC TV serial is a better representation of the book.

The Ruins (2008) is a guilty pleasure.

Agree with the above thoughts on the Triffids book & adaptations. The unmentioned 2009 mini-series is truly awful.

Ooh almost forgot to mention the “Creeping Vine” segment of the Hammer horror anthology film Dr. Terrror’s House of Horrors (1965) might actually be my favorite. It’s been too long since I’ve seen it to be positive, however.

Lil Shop all the way.

List of plant monster movies: https://www.imdb.com/list/ls561959422/

Little Shop of Horrors musical is the best I can think of right now.

Bonus: The Revenge of Doctor X is the worst. Ninety minutes of padding, then there's some mayhem with some villagers revolting and the Dr. leading the plant into a volcano, but by then I doubt anyone cared. To be honest, i had to look up the ending on Wikipedia to refresh my memory.