It depends on how much room you have and how much you expect to yield. Yield is more about square feet and style of grow than overall number of plants. Sea Of Green is a style that requires a whole lot of plants, maybe as many as one per square foot, so as many as 16 plants in a 4 foot by 4 foot space and maybe even more with really small clone SOGs. You could also grow only one plant in a 4’x4’ and yeild the same overall weight at the end of harvest with a Screen Of Green, in this case you would need netting, but this is kinda an advanced technique and is probably not what you wanna try your first grow.
A 4’x4’ is probably a good size for most people that are just growing for themselves or a very small group of people, and something at least 5 feet tall, to have room for about any type of lighting you might choose. 3 to 4 plants evenly distributed in the floor space and allowed to grow relatively untrained is probably the best for a brand new person as you kinda need to learn and understand how the plant grows, what parts of the plant do what or turn into what and thereby you will know later what can be cut off or what parts can be bent to fill out a net on future grows.
LEDs will be the best for not having to invest a lot in a ventilation system that will be powerful enough to move enough air to keep other hotter lights heat down, but are among the more expensive lights to start with and the hardest to find a good preforming model that won’t break the bank. I can’t recommend any of the more reputable LED name brands as I feel they are highly over priced and not significantly better than equivalent models from lesser known brands that may be as much as 50%-75% cheaper. All I can say is do a lot of diligent research and you should be able to find an affordable model that will suit your needs and with a company that has a good enough reputation to fix or replace if any of the individual LEDs burn out.
In my opinion LEDs are your best option overall. Latewood likes the very affordable 400 watt HID, adjustable digital ballast, system. It’s mostly up to you and what will suit your needs best.
You also need to figure out if you are going to want a nursery and or vegging room/tent/cabinet or you are always going to grow from start to finish in the big grow tent – which would mean longer periods between harvests than if you have plants in a vegging room getting big enough to replace a plant that was just removed from the flowering room.
Humidity is a big concern, a fan circulating air in the tent is needed (a small oscillating desk fan will do) as well as a inline type to actually bring fresh air from outside to inside the room. You don’t necessarily need and inlet fan and an outlet fan, you can run negative pressure in the tent by only having one inline fan pushing/pulling air out of the tent and fresh air would be sucked in through vents and or seems.
All of our seeds are great for indoors or outdoors but the more compact indica dominant strains are a good idea to start off with in tight spaces.