GH Flora Series 3-part. I used it with the so-called "useless" schedule. One thing I didn't like is that I didn't know what NPK I was feeding when I mixed 3 bottles to varying ratios. I documented what the NPK ratios were
here (<<link), and that has a link to the schedule itself.
That's a hydroponic nutrient. I used it with Pro-Mix HP (soilless) with 20% perlite added. If you're under HID lights you may want to use Pro-Mix BX, it has vermiculite and doesn't dry as fast.
I think it's a good nutrient for a beginner. The only thing I added was Liquid Karma and Kookbloom liquid & powder in bloom.
If you grow in soil or soilless, fast drainage is more important than the nutrients you choose. You want the soil to dry such that you can water every 2-3 days. With HP and 20% perlite, I was doing 2 days. You should also add 1-2 Tbsp dolomite lime per gallon of medium (powdered, not pellets).
I moved onto Grow More Sea Grow, which contains organic ingredients. It's inexpensive, about $1 per plant, per grow. I got tired of the tedium of mixing 3 parts. And, liked the taste organic nutrients impart on the smoke.
I think 3-part is good for beginners because the "schedule" gives them a safe outlet to feel like they're participating at the level their inclined to (instead of killing their plants with kindness). It's a little more immediate. If you overfeed you'll get burnt tips the next day or two (by contrast, my Grow More Sea Grow is slower. I don't get burnt tips, just acidic soil which is harder to detect for a new grower.). The varying NPK ratios help a new grower with "reading" their plant, thinking about what they're giving and what they're seeing. Overall, it's like guardrails (or training wheels). But, there are experienced growers using 3-part too. It's just suited (IMO) to new growers in a unique way.
Get a ph and TDS pen. PM me and I can give you links to cheap ones on Amazon that have worked well for me.