Recommend Some Hosts

Well, it depends if you want to take the time to learn how to use Linux terminal, most large minecraft servers are hosted on Linux with no fancy desktop gui. Also make sure it isn't a VPS server. You want a real solid physical server. I would start looking at places like OVH.com which gives you more bang for your buck but you must note, their staff does not help you at all other than if your server stops working and you need it reset up completely.

If you are new to this and never really hosted servers before, then go with multicraft, they should be able to help you. They have a very nice support team if they still do bungee and spigot support. Fragnet might also be a good choice but I am not sure if they support spigot.

Also a little background about bungee and spigot. Spigot is like Bukkit and infact built off of bukkit but it allows servers to connect via each other directly and form networks like you wanted. Bungeecord is the actual proxy server which redirects players to different servers on your network. These two are essential if you are looking for network hostings among multiple servers.

If you are looking to form a network like mineplex and ect, those are multiple server put together. They do not use hosters and use raw servers. They host on Linux server with nothing but terminal, ftps, and probably their own built GUI. You do not want to go with a minecraft specific hoster as they will restrict your RAM and try to sell you their GUI and licenses which end up raising the price like 5$ more per RAM.

So my advice is to get an empty basic server and not a presetup one that some company does for you. That is basically cutting out the middle man that takes money from you that you could be using towards the server. But if you are new, however, use fragnet or multicraft. Multicraft may be the one best for networking as I believe they offer bungee servers and spigot support.