NEO is seen as the Ethereum of China and is currently the fifth largest cryptocurrency in terms of market cap. It is often viewed the be a rival to Ethereum as it is believed that its value in the future should overtake that of ETH. The prices for both NEO and GAS have soared high up but are still quite solid investments you can take.
If you aren't aware of the difference between GAS and NEO, allow me to give a brief explanation. NEO is a token that can be seen as a share of the company, in this case it is a share of the blockchain; much like stocks. Each NEO you own will generate GAS on a daily basis. GAS is simply the currency of NEO, which will be used for transactions and will also be used to fund ICOs in the coming year.
NEO=Stocks
GAS= Currency
One reason to invest in GAS is if you invest in NEO and keep your NEO in the exchange (Bittrex), the GAS your NEO generates will be kept by the exchange and you will have no way of claiming your GAS unless you decide to store your NEO in a personal wallet. Binance (chinese exchange), however, doesn't claim your GAS. Even if you do so, the ROI of investing NEO at least for small-medium capital investors is significantly lower than investing into GAS as GAS' value is expected to overtake that of NEO in the exchange in the future. More importantly, you will need around 2200 NEOs to generate at least 1 GAS per day. 2200 NEOs at current marker price is around $101,200.
If you do decide to get GAS or even NEO you can get them at Binance, which trades against BTC. Remember to turn your VPN off when you register in the exchange. You will not be allowed to register with a VPN on.
You can calculate your ROI for NEO here: https://neotogas.com/
I am not a financial expert and am simply giving my own opinion on the topic.