What is currently the best Firewall device for medium and Enterprise Companies?

Cisco ASA is easy for deployment and can manage multiple ASAs with Cisco Security Manager for policy pushing, monitoring and health maintenance but if you are looking for deep packet inspection of applications which inside inferior user encapsulate within well-known ports and try to bypass the network for not appropriate purpose then Palo-Alto us very good option which is also Next generation firewall which can even inspect SSL traffic and establish a secured connection between client and server. 

Juniper SRX firewall are also equally powerful for enterprise environment where you can use zones and assign physical interfaces to respective zones which can control the traffic within zones and keep the environment safe. 

Checkpoint firewall is also very user friendly and easy for administration by Smart tracker , Smart monitor and smart update. 

You can select the firewall based on your enterprise requirement and throughput which decide how fast your traffic should get inspected. 

That is really important question

I guess Cisco ASA (Adaptive Security Appliance) 5500 Series combines firewalls, VPNs and more for small to medium-size business clients. As part of that series, the ASA 5505 Security Appliance w/50U VPN Peers, is an adaptive security appliance firewall tailored for SMB clients with one or a few locations. Features for the 10-user bundle solution include an 8-port fast Ethernet switch, 10 IPsec VPN peers, 2 premium VPN peers, triple data encryption standard and advanced encryption standard license.