I use all the modalities: barbell, kettlebell, bodyweight, dumbell, machines, and odd objects. They all are great. But that doesnt mean one cant be strong and healthy just choosing one of them. And, of course, one can accomplish everything with 1 modality, but it may not be the most efficient way to do so.
Here is my personal view on each one:
Barbell - It is best for absolute strength and mass. The barbell is the my primary modality. Specifically, the lower bar back squat, deadlift, and bench press (the powerlifts). I dont do these excersises because of my love for powerlifting. I have competed twice. I powerlift because I'm convinced it's the best way to get as strong as possible. This modality has had a lot of carryover to the others. For example, adding weight to my bench press has increased my kb press or swing or snatch bell size much more than when I specifically trained those lifts, exclusively.
Dumbell - The best option for progressive overload of unilateral grinds. I love using dumbells for good, old fashioned, high rep and low intensity hypertrophy work.
Kettlebell - My favorite and the most "fun" to perform. The kettlebell is probably one of the most versatile modalities. But where it shines, in my opinion, is: (1) Low financial and low skill, (2) Ballistic speed/power training, (3) The grip. For (1), I mean 1 kbell is versatile and can act as a whole workout. 1 kbell is not that expensive. Also, learning complicated full body Ballistic excersises is much simpler, and safer, than learning their counterparts in other modalities. (2) Speed training with swings and snatches is really important for athleticism. Being able to train heavy snatches and swings has so much carryover to other things, and it is difficult to replicate this (although not impossible) with other modalities. Also, there is the "conditioning" aspects of it as well. (3) The Grip. Kbells will accidentally buildup your forearms and hands. This has tremendous carry over to life. We interact with our physical environments primarily through our hands! If I was forced to choose 1 modality, it would probably be the kbell. One downside, and it is a big one, is the inability to train the lower body with heavy weights. Because of this, the kbell is inferior to barbells for absolute strength training.
Bodyweight - Obviously the most accessible. Not always intuitive, it can be the hardest to master, but also a great place to start for beginners. I do daily bodyweight excersises for my core training to ensure I never experience back pain again. McGill Big 3 for example. Pullups, pushups, bodyweight squats (goblet), and many mobility/stability excersises are part of my daily routine. For me, proper movement/stability where it counts plus core strength.
Machines - I like machines! They are new to me, only been using them a year or so. They are restorative after a heavy barbell session. They get my blood flowing, make joints feel lubricated. I love how they allow for a lot of volume, a ton of hypertrophy volume training, without having to demand much neural energy. What do I mean by that? There is so much of a mental component of the other modalities, I like that I can turn off my brain and just do some machine chest presses. It is very "punch the clock" for me. Machines, in parallel with dumbells, can build an impressive physique. I state this because there are some "swole" folks at the Planet Fitness I attend 1 day/week. I find that I really miss my weekly PF workout, now that we are in social isolation. However, I'm easily able to replace it with my kbells, bowflex adjustable dumbell, and heavy bands.
Odd Objects - Great for strength endurance, grip, and a lot of fun. They also build "grit", mental toughness, more so than a lot of other modalities. I use sandbags and farmers walks as Finishers. I also like weighted vests. For a true minimalist, I think doing some carries/squats/presses with heavy sandbags mixed with kbel swings/snatches would be a great combination.